Sensor and method of manufacturing the same
Disclosed is a sensor and a method of manufacturing the same. The method includes forming a plurality of electrodes on a substrate and forming a sensor layer on the substrate between the plurality of electrodes. The forming of the sensor layer includes coating a nanoparticle layer, providing deionized water on the nanoparticle layer to form a spontaneous transition layer, and annealing the spontaneous transition layer to form the sensor layer.
1. A method of manufacturing a sensor, the method comprising:
forming a plurality of electrodes on a substrate; and
forming a sensor layer on the substrate between the plurality of electrodes, wherein forming the sensor layer includes:
coating a nanoparticle layer to the substrate;
providing deionized water on the nanoparticle layer to form a spontaneous transition layer which includes cobalt hydroxide; and
annealing the spontaneous transition layer at a temperature of 300° C. to 700° C. to increase lifespan and response characteristics of the sensor layer.
2. The method of claim 1 , wherein
the nanoparticle layer includes a first cobalt oxide (CoO).
3. The method of claim 1 , wherein
the nanoparticle layer has hexagonal pyramid-shaped nanoparticles.
4. The method of claim 1 , wherein
the sensor layer has a response and long term stability, which are 0.6 to 0.7.
5. The method of claim 1 , wherein
the sensor layer includes a second cobalt oxide (Co 3 O 4 ).
6. The method of claim 5 , wherein
the spontaneous transition layer is annealed at a temperature lower than a melting point of the second cobalt oxide.
7. The method of claim 1 , wherein
the annealing temperature is 500° C.
8. The method of claim 1 , wherein
the spontaneous transition layer has a first plate crystal, and
the sensor layer has a second plate crystal similar to the first plate crystal.
9. The method of claim 8 , wherein
the second plate crystal has a hexagonal octahedron shape.
10. The method of claim 1 , wherein
the nanoparticle layer has a first thickness, and
the spontaneous transition layer has a second thickness smaller than the first thickness.
11. The method of claim 10 , wherein
the first thickness is 600 nm, and
the second thickness is 300 nm.
12. The method of claim 10 , wherein
the sensor layer has a third thickness equal to or smaller than the second thickness.
13. The method of claim 12 , wherein
forming the sensor layer further includes forming a preliminary sensor layer having the third thickness.
14. The method of claim 1 , further comprising:
forming a heater electrode on a bottom surface of the substrate facing the plurality of electrodes and the sensor layer.
15. The method of claim 1 , wherein
forming the sensor layer further includes preparing nanoparticles, and
the nanoparticles are prepared according to a standard Schlenk line technique.
16. The method of claim 15 , wherein
preparing the nanoparticles includes:
obtaining a mixed solution of cobalt acetylacetonate and benzyl amine;
stirring the mixed solution to precipitate the nanoparticles; and
removing supernatant in the mixed solution to extract the nanoparticles.